<script type="text/javascript">

    var currentIndex = 0;

    function changeBg() {

        //定义要切换的背景图片，双引号里面"1.jpg","2.jpg","3.jpg","4.jpg"，可以放任意多个用,隔开

        var bgImgs = ["1.jpg","2.jpg","3.jpg","4.jpg"];

        if (currentIndex >= bgImgs.length)

            currentIndex = 0;

        $("#divbanner").css("background-image", "url(" + bgImgs[currentIndex] + ")");

        currentIndex += 1;

    }

    setInterval("changeBg()", 2000); //设定定时切换，单位为毫秒这里是3000 毫秒

</script>

<div id="divbanner" class="banner" style="background-image:url(<%= strhomeAdvertisement_1%>);">

</div>